Blasting plug



R. J. HEITZMAN 2,007,568

July 9, 1935.

BLASTING PLUG Filed Deo. 6, 1934 www aan n, 9, 1935' 2,007,568

l UNIT/ED STATES PATENT ori-ucla i BLASTING PLUG melma .1. Henman, shamdlnn, ra, assigner of one-fourth 4to William E. Bessler, Shamokin,Pa.

Application December s, 1934, sei-iaiv No. 156,319

' yz (ci. 1oz- 11) This invention relates to blasting plugs and the numeral I represents a. mass of coal or rock it is an improvement upon the masi-,ing plugs in which is drilled thebore or hole 2, the remote illustrated and described in lmy eepending apportion of the hole being filled with the sticks plication for patent, Serial N0, 747,435, med Oc-- 3 of dynamite or other suitable explosive to -5 tober 8, 1934. l which lead the electric wires 4 terminating in 5 ,One of the objects of the invention ls to pr a -fulllflinal'fng Cap 5 inserted in the end 0I the vide a plug of elastic material such as rubber, dynamite It S Customary in the art 00 i111 the having a taperedinsert seating in arecess inthe anterior partV of the hole with small bags 0f outer end and adapted Ato be forced into the Sand 01' earth tamped intO place, the Operation lo recess after the plug is in place. in the drilled being knQWn aS Stemming. The sand or earth hole in the rock or coal, for expanding the outer being quite abrasive, it frequently happens that end of the plug lcompressively against the surthe insulation is worn off of one or both of the rounding wall of the drilled hole, making a, gaselectric wires grounding them, so that when the tight' seal and immovably xing the plug in circuit is closed, a misre occurs and no ex- ]5 position.- Y Y f. O f plosion takes place. Since al number of charges u Another object of the invention is to provide. are Set off simultaneously, it iS frequently ima blasting plug that shall oifer no incentive for DOSSible t0 ascertain which if any 0f l311e Charges its removal in case of misere, thus euminating failed to eXplOde and an unexploded charge may the dangerous practice of drilling out the plug, be thrown down to the floor of the mine or quarry A furtherV object object of the invention is to by the breaking up 0f the I'Oek 01 Coal CausedA 89 Vprovide a. blastingiplug that shall obviate the by an eXPlOSOn 0f adjacent Charges. The unneed of stemming the bore in the coal orrrock. exploded dynamite iS frequently .indistinguish- Still another object of the inventionis the proable from the debris and there is the hazard vision ofa blasting 'plug so constructed asl to of the miner striking it with his Piek and eX- v2115' cause the explosion to bring down an increased i plodng it with the loss of life or limb. In any g5 amount of coal or rock and produce an increase event, stemming is a time-consuming and in the percentage of large pieces. vexpensive operatnn. i Other objects ofthe invention will appear-as The Plug' 0f iThe Present invention Obviates the following description of a preferred and practhe need of stemming, for it is designed to be tical embodiment thereof proceeds. held in place initially prior to the explosion and so In the drawing which accompanies and forms further fixed in position by the force of the exa part of the following specincation, and plosion. With this end in view, the plug is formed throughout the several ilgures of which the same with a cylindrical body of rubber or other subcharacters of reference have been employed to stance capable of expanding uniformly in a radial designate identical parts: v direction. In its initial shape it just freely nts 35 Figure 1 is a longitudinal section of a hole the drilled hole so that it can be slipped into place drilled in the coal or rock showing the explosive by the mere pressure of the tamper. In its outer inplace and a blasting plug embodying the priri-A .andthe plug 6 is provided with a well or de- 'ciples vof the present Ainvention in place, but not, pression 1 preferably cylindrical in its outer porad as yet, in expanded condition; tion or slightly flared. An insert 8 seats in said o Figure 2 is a longitudinal section through the depression, being larger in diameter than said blasting -plug showing thev tapered insert driven 'depression atl its outer end and tapering vtowards home, expandingv the periphery of the outer vits opposite end which is suioiently small to ex- Y end ofthe plus; tend freely within said depression. The insert i5 v Figure 3 is a longitudinal section through the may be made of rubber or of any other suitable 45 plug showing its condition immediately followmaterial. It is not necessary that it be yielding ving an explosion; y since its objectl is to deform or spread the outer Figure 4 is a' section taken along the line 4-4 end of the plug 6 when driven into said depresof Figure 3V illustrating the manner in which sion. After the plug 6 has been pushed gently 50 the plug yields to embedthe wires; and into position against the explosive charge, theA 50 Figure 5 is a longitudinal section through a tamper is then forcibly pushed or struck against' modied form of plug-illustrating a tapered in-V the end oi?4 the' insert 8l driving it into said de.- sert with ang base .producing ,a peripheral pression. The rubber or other explosive material lip at the outer end of the plug. of which the plug is .made is radially diverted as 'i-f Referring now in detail to the several heures indicated at 9 in Figure 2, defining a peripheral 55' seal as at l in Figure 3, and holding the plug -irmly against displacement.

It is absolutely essential in order for the explosive to exert its full force against the coal or rock that the explosion chamber be sealed against escape of the gases of explosion, at the moment of explosion, otherwise the intensity oi. the pressure is greatly lessened. It is due to the perfect seal indicated at I0 that the plug of my invention causes the explosion to bring down a greater amount of coal or rock than would otherwise be the case.

On account oi' its elastic quality and the fact that it is relatively heavy and therefore possesses considerable inertia, the plug retains itself in position despite the intensity of the explosion and therefore requires no stemming, At the instant of explosion lthe pressure against the irmer end of the plug expands it radially .compressing it against the wall of the drilled hole as indicated at Il throughout an extensive area jamming it in the hole and preventing its being blown out. It will be observed from Figures 3' and 4 that when the anterior end of the plug is expanded by tamping, and later when the inner end is expanded through the force of the explosion, the rubber or othermaterial yields to the presence of the wires 4 as indicated in Figure 4, so thatthe wires embed themselves in the body of the plug and are safeguarded from abrasion. Initially, if the plug is a tight enough ilt in the drilled hole, the wires press against the surface of the plug as it is shoved in, forming a seat in which they are yieldingly embedded.

In view of the fact that stemming is not necessary and that only a light blow of the tamper is essential to drive the insert 8 into the depression 1, the wires are not subject to abrasion, consequently, a short circuit is not likely to occur and there is practical assurance that the explosion will take place. In the event that a misilre does occur, the explosion may be induced by firing a charge oi dynamite against the outer surface of the plug.

In view of the yielding nature oi' the material of which the plug 6 is made, the impact of the explosion is slightly cushioned, so that the force of the explosion is not so much expended in shattering the proximate mass of rock or coal, but is given them for transmission deeper into the mass, throwing down more coal or rock and larger pieces. It is preferred as has been previously stated to make the plug of rubber, although any other material or composition having like characteristics is within the purview of the invention. The selection of material for the insert 8 is not very critical since the relative hardness or softness does not matter providing of course that the insert is rmer than the material of the plug 6 so .that it can transmit a deforming pressure to the plug. I

Figure 5 shows a slightly modified form of the invention in which the insert I2 differs from the insert 8, previously described, in having a flared peripheral flange I3 at its outer end. When the flange portion of this insert is driven into the depression l of the plug, the material of the plug is deformed so as to throw out a relatively thin lip I4 peripherally of the outer end of the plug. This lip extends towardthe exterior of the hole and tends to push obliquely against the wall of the drilled hole in a direction to become more tightly engaged with said Wall as the force which would displace the plug outwardly increases. This is an added safeguard against the blowing out of the plug under the force of the explosion.

While I have in the above description disclosed what I believe to be a preferred and practical embodiment of my invention, it will be understood by those skilled in the art that the details of construction as herein illustrated and described are merely by way of example and not to be construed as limiting the scope of the invention as claimed.

What I claim is:

1. Blasting plug comprising a body of yielding rubber adapted to be inserted in a drilled hole in coal or rock adjacent a mass of explosive, said body having a recess in its outer end and a tapered insert normally seated in the anterior portion of said recess and adapted to be forced deeper into said recess for expanding the external periphery ofthe outer end of said plug into compressed relation to the walls of said drilled hole,

the inner portion of said bodyextending beyond any other part of said plugso as to expose said portion direct to the explosion pressure, thereby providing a yielding cushion for mollifying the -shattering effect of the explosion, and adapted to be expanded by the pressure of the explosion into sealing relation to the wall of the drilled hole.

2. Blasting plug comprising a non-metallic unit consisting of a body composed wholly of yielding rubber adapted to be inserted in a drilled hole in coal or rock, having a recess in its outer end and atapered insert normally seated in the anterior portion of said recess, and adapted to be forced deeper into said recess for expanding the external periphery of the outer end of said plug into compressed relation to the Walls of the drilled hole, the inner portion of said body ex tending beyond any other part of said plug so as to expose said portion direct to the explosion pressure, thus providing a cushion for yieldingly resisting the explosion yto mollify the shattering effects thereof, and the inner end of said body being adapted to be expanded by the pressure of the explosion into sealing relation to said walls.

RICHARD J. HEITZMAN. 

